1. Field of Invention
This invention relates to fuel cell batteries, and, more particularly, to fuel cell batteries requiring refueling of anode material, replacement of anode structures, replacement of cathode structures, and/or electrolyte maintenance.
2. Description of Related Art
A fuel cell is a device that converts the energy of a fuel (metal hydrogen, natural gas, methanol gasoline, etc.) and an oxidant (air or oxygen) into useable electricity. A fuel cell construction generally consists of a fuel supplying electrode (anode) and an oxidant electrode (cathode) separated by an ion conducting medium. A fuel cell stack is comprised of numerous individual cells stacked together to provide the required power. Unlike traditional fossil plants that combust fuels, fuel cells generate electricity through an electrochemical process from which no particulate matter, nitrogen or sulfur oxides (NOx or SOx) are produced. As a result, they do not contribute to the formation of smog and acid rain.
Metal-air fuel cells convert metal fuel (such as zinc or aluminum) and an oxidant (such as air or oxygen) into electricity. Examples of metal-air fuel cells are described in detail in WO99/19628, entitled xe2x80x9cMetal-Air Fuel Cell Battery Systems Employing Metal-Fuel Cardsxe2x80x9d, WO99/18627 entitled xe2x80x9cMetal-Air Fuel Cell Battery Systems Employing Metal-Fuel Tapexe2x80x9d, and WO99/18620 entitled xe2x80x9cMetal-Air Fuel Cell Battery Systems Employing Moving Anode And Cathode Structuresxe2x80x9d, U.S. Pat. No. 5,250,370, incorporated herein by reference, and other applied science publications well known in the art.
Hydrogen-based fuel cells convert hydrogen fuel and an oxidant (such as air or oxygen into electricity. An example of a hydrogen-based fuel cell is described in WO 99/60642, entitled xe2x80x9cMulti-element Fuel Cell Systemxe2x80x9d, published May 5, 1999.
Various means have been used for holding the cells in position relative to each other and for electrically interconnecting the cells. Often these means are unrelated and accordingly there is a substantial volumetric loss, excessive complication of elements and overall weight, as well as difficulty in removing and servicing the individual cells. In addition, such fuel cell battery holding structures typically employ an enclosure to house the cells, which renders the enclosed cells difficult to access, replace, or service.
For fuel cells, ease of service is of particular importance because such cells require servicing and replacement of depleted materials in order to work over an extended period of time. More particularly, such cells may require replacement of anode structures, replacement of fuel, replacement of cathode structures and replenishment of electrolyte (or other ionically-conducting medium).
It is accordingly an object of the present invention to provide a fuel cell battery device or system with a structure providing integrated fuel cell stacking, mechanical support, and fuel cell electrical interconnection.
It is a further object of the present invention to provide a fuel cell battery device or system which permits quick removal and electrical interconnection of fuel cell elements for service (including replacement of anode structures, replacement of fuel, replacement of cathode structures and replenishment of ionically-conducting medium).
It is yet another object of the present invention to provide a fuel cell battery device or system which includes means for air circulation for use with air depolarized fuel cells.
It is a further object of the present invention to provide a fuel cell battery device or system having a structure that independently and releasably engages each of a plurality of fuel cells to thereby mechanically support the fuel cells so engaged.
It is a further object of the present invention to provide a fuel cell battery device or system having a structure that independently and releasably engages the cathode assemblies and anode assemblies of a plurality of fuel cells to mechanically support the cathode assemblies and anode assemblies so engages, and provide electrical connection to the cathode assemblies and anode assemblies so engaged.
It is a further object of the present invention to provide a fuel cell battery device or system that includes a support structure that independently and releasably engages the cathode assemblies and anode assemblies of a plurality of fuel cells to provide electrical connection to the cathode assemblies and anode assemblies so engaged, and that includes an integrated interconnection means that can configure the plurality of fuel cells into a desired interconnection arrangement.
It is a further object of the present invention to provide a fuel cell battery device or system that includes a support structure that independently and releasably engages a plurality of fuel cells along one side of the fuel cells, leaving the other sides (e.g., the top and far side of a plate-like fuel cell) exposed for the ready replacement of the anode, cathode, or the ionically-conducting medium of the individual fuel cell disposed therein.
Generally the present invention comprises a fuel cell battery structure comprising at least two fuel cells and an electrical connector block. The fuel cells are electrically interconnected into a battery structure via the connector block. Each fuel cell comprises an anode and cathode element and each of the anode and cathode elements of each cell are provided with a terminal a conductor element externally positioned on one side of the respective fuel cells. The connector block comprises a series of conductive elements adapted for electrical and mechanical engagement with the respective terminal conductor elements of the anode and cathode elements of each of the fuel cells on said one side of the respective fuel cells. The connector block further comprises means for electrically connecting the anodes and cathodes of the stacked cells into a desired electrical interconnection. In addition, the block mechanically holds the respective fuel cells on one side of the block, in a fixed position as a result of the mechanical engagement. As a result, another side of each of the fuel cells remains exposed to permit disengagement and removal of the fuel cells from the block.
Generally the present invention comprises means for forming a stack of fuel cells into a unique overall fuel cell (in particular air depolarized cells such as zinc/air cells) or battery system, wherein a single structural element provides means for cell support and slacking and electrical interconnection of the cells into a desired electrical configuration. In addition, the structural element is preferably configured with air duct means to facilitate air circulation to the individual cells, with concomitant increase in discharge rate capability.
In a preferred embodiment of the present invention, flat plate fuel cells and batteries of cells, particularly air-depolarized cells, are stacked and electrically interconnected into a battery system with a connector block and optional support tray. The anode and cathode elements of each cell are provided with terminating elements, preferably extending in a downward xe2x80x9cUxe2x80x9d shaped configuration from the upper ends of the anode and cathode elements respectively, to provide maximum physical support. However, other extension configurations (e.g., upwardly extending, laterally extending, etc., as well as reversal of the male and female elements) are similarly operable and are included in the present invention.
In a preferred embodiment the connector block comprises a series of conductive apertures, positioned and sized to accommodate the terminal conductor elements of the electrodes therein. The connector block further comprises electrical interconnecting elements to electrically connect the electrodes of the stacked cells in a desired electrical interconnection (serial, parallel and mixed serial and parallel segments). Preferably male and female plug connections, embedded within apertures in the connector block, are used to mate with the anode and cathode terminating elements of the fuel cells, to effect both the electrical interconnection and mechanical support between the cells and the connector block. The interconnection between anode and cathode terminating elements and the respective apertures further serves to support and orient the cells in a minimal volume and permits selective rapid cell removal for replacement or servicing. The cells are also preferably provided with keyed members for keyed interlocking with a support tray having co-fitting keying elements to provide full structural integrity for the stacked cell. Lateral end elements extend the connector block and support tray to complete an open enclosure and provide a support base for air circulating devices, such as fans, in an xe2x80x9cair management systemxe2x80x9d and also support the block in a suspended position suitable for engagement with the individual fuel cells.